| 摘要 |
PURPOSE:To obtain the titled compounds useful as a raw material for pyrethroid based insecticides, by carrying out recemization of optically active chrysanthemum-monocarboxylic acids in the coexistence of a specific racemizing agent with a peroxide, etc. CONSTITUTION:Optically active chrysanthemum-monocarboxylic acids expressed by the formula (R is H, 1-20C alkyl, cycloalkyl or aralkyl; * indicates asymme tric carbon), such as levo-rotatory chrysanthemum-monocarboxylic acid, are reacted and racemized with at least one compound selected from carboxylic acid bromides, such as acetyl bromide, silicon bromides, such as trimethylsilyl bromide, thionyl bromide and N-brominated compounds, such as N- bromosuccinimide, in the presence of a peroxide, such as tert-butyl hydroperoxide, or azo compound, such as azoisobutyronitrile, in an inert solvent, preferably toluene, etc., at -20-+100 deg.C for several min - 10hr to afford the aimed racemized optically active chrysanthemum-monocarboxylic acids. |
